1. Field of the Invention
The invention relates to a ventilation system for a liquid-filled basin.
2. Description of the Prior Art
Diverse ventilators are well-known for liquid-filled basins, which have a ventilation device rather complicated in design. The connection of the ventilation device of necessity includes intensive installation and a bulky guide arrangement. A further disadvantage is that maintenance, repair, and replacement of components of the ventilation system are very complicated and labor-intensive.
In the DE-OS 36 27 655.0-23 an improved ventilation system is disclosed, in which a ventilation hose is laid in a permanently installed upwardly open U-profile guide anchored below the liquid surface and held fast by straps which extend over the hose. The hose is pulled in the U-profile guide under prestress.
Prestressing of the ventilation hose has not proved in practice to be effective. The concept described in DE-OS 36 27 665.0-23 to effect a freeing of the perforation of the ventilation hose from deposits, blockages, etc. through variation of the prestress and the resulting extension in length is not effective, since problematic deposits cannot be removed in this fashion. The high prestress of the hose, which entails considerable mechanical apparatus, leads in the long run to a plastic deformation of the hose, which necessarily requires that it repeatedly be shortened, until finally the material is exhausted after a relatively short useful life. The perforation holes are expanded by the prestress which leads to an undesirable increased intrusion of water in the ventilation hose when the prevailing air pressure drops off. The air bubbles also become larger through the expansion of the holes so that the utilization of oxygen is less efficient; the effect of ventilation is reduced.